Friar Broccoli wrote:
On Aug 13, 8:38 pm, John Harshman
wrote:
K_h wrote:
Fermi's paradox suggests that there are little or no other intelligent
civilizations within the Milky Way galaxy. On the other hand, intelligent
life should exist on a substantial fraction of planets with life because
natural selection broadly increases intelligence with time.
Does it? News to me. What evidence do you have that this is the case?

There has been an increase in the intelligence of a broad range of
species on earth with time.

Has there? What broad range, exactly? And if natural selection broadly
increased intelligence with time, we would expect all species to be
undergoing this push, wouldn't we? Yet we see that brains exist only in
a small subset of species within one restricted clade (Metazoa), and
that, depending on how you define the word, complex brains exist only in
a small subset of those (which I will choose to interpret here as
Cephalopoda and Gnathostomata), and that particular complex ones exist
only in a small subset of those (Aves and Mammalia), and that only one
species has human-level intelligence, and from observing usenet, that
only rarely. It's hard to consider this a general trend. Similar results
could be achieved by random diffusion starting at a barrier, with a
great deal of variance in the intelligence of the extreme tail.